携带HPI毒力岛的大肠杆菌的毒力基因分析

Genomic analysis of the virulence genes in Escherichia coli harboring high pathogenecity islands of Yersinia enterocolitica isolated from diarrhea patients

目的检测分离自腹泻病人、家禽粪便和食品标本的携带HPI毒力岛的大肠杆菌携带其他致病性相关基因组岛的情况。方法运用PCR和DNA打点杂交方法。结果在被检测的82株大肠杆菌中,志贺氏菌属的Shi-2岛检出率为62.2%(51/82);大肠杆菌O157:H7的8个O岛中,OI55和OI140的检出率为57.3%(47/82),且二者协同存在;OI28的检出率为35.4%(29/82),OI115的检出率为68.3%(56/82),OI144的检出率为9.8%(8/82),OI43和OI122则均未检出。该82株大肠杆菌中78株携带至少2个毒力岛,如编码RTX的OI28岛、编码III型分泌系统的OI115岛以及编码粘附素的OI144岛,另外还有4株菌携带7个基因岛,20株菌携带6个基因岛。结论一些和细菌致病性有关的基因组岛在肠道大肠杆菌中广泛存在,其中一部分有可能是致病性的,提示基因横向转移在致病性大肠杆菌进化过程中具有重要意义。

With irp2 （iron repressible protein 2） gene as probe, we had isolated strains of E. coli harboring the high pathogenicity island （HPI） of Yersinia enterocolitica from diarrhea patients, domestic animals and food samples. The aim of the present study was to determine the virulence factor patterns of these isolates, in which 82 isolates were detected by both of PCR and DNA hybridization. It was demonstrated that in these 82 isolates of E. coli, the detection rates of Shi-2 island from Shigella was 62.2% （51/82） ; in 8 O-islands from E. coli OI57 ： H7 the detection rate of co-existence of both OI55 and OI140 was 57.3% （47/82）; the detection rates of E. coli OI28, OI115 , OI144 were 35.4% （29/82）, 68.3% （56/82） and 9.8% （8/82） respectively, while OI43 and OI122 were not detected . In these 82 isolated strains of E. coli 78 strains habored at least two high pathogenicity islands, such as OI28 island coding for RTX, OI115 coding for the type Ⅲ secretion system and OI144 island coding for putative adhesins. In addition, there were 4 strains of isolates harboring 7 genomic islands and 20 strains harboring 6 genomic islands. From the above observations, it is apparent that the genomic pathogenicity islands involving in the virulence of bacteria exist widely in E. coli isolated from diarrhea patients, domestic animals and food samples, in which parts of these isolates may be pathogenic, indicating the great significance of lateral gene transfer in the evolutionary course of pathogenic E. coli.